Terminal apparatus, data transmitting apparatus, data transmitting and receiving system, and data transmitting and receiving method

ABSTRACT

A terminal apparatus transmits a data requesting packet requesting transmission of desired data and having information indicating capability of the terminal apparatus attached thereto to a data transmitting apparatus. The data transmitting apparatus receives the data requesting packet, detects the information indicating the capability of the terminal apparatus from the data requesting packet received, receives information on a state of a network, the information being transmitted from a network monitoring apparatus, and transmits data based on the detected information indicating the capability of the terminal apparatus and the received information on the state of the network to the terminal apparatus via the network. The terminal apparatus receives the data transmitted from the data transmitting apparatus, decodes the received data, and outputs the decoded data.

BACKGROUND OF THE INVENTION

The present invention relates to data transmission via a network, andparticularly to a terminal apparatus, a data transmitting apparatus, adata transmitting and receiving system, and a data transmitting andreceiving method for controlling transmitted data according tocapability of the terminal apparatus.

In contents distribution by video-on-demand service, distribution oflive video, or real-time communication such as videoconferencing, thevideophone and the like, a system is devised which transmits dataappropriate for capacity of terminal apparatus having differentperformances which data is obtained from the same source data to theterminal apparatus, using a layered coding (scalable coding) technique.

Conventionally, a server apparatus or the like on a data transmittingside is required to prepare a data file in a different format accordingto capability of a terminal apparatus to which to transmit data orprepare a different data file according to a transmission rate.

However, the use of the layered coding technique enables data from asingle data file to be distributed simultaneously to terminal apparatushaving different performances, for example a terminal apparatus having adisplay with a low resolution and a CPU (Central Processing Unit) with alow processing capability, such as a portable telephone or the like, anda terminal apparatus having a monitor with a high resolution and a CPUwith a high processing capability, such as a desktop personal computeror the like.

For such data transmission according to the capability of the terminalapparatus, information indicating the capability of the terminalapparatus needs to be notified in advance to a server apparatus or thelike serving as a data transmitting apparatus, and a complicatednegotiation or the like is required between the terminal apparatus andthe server apparatus.

In the case of a terminal apparatus such as a PC (Personal Computer)having various advanced functions and including an OS (Operating System)with a high processing capability, for example, it is easy to implementa protocol for notifying the information indicating the capability ofthe terminal apparatus and performing the negotiation with the serverapparatus as described above.

Recently, however, an IP (Internet Protocol) address is given even to aportable telephone whose data processing capability is not very high andwhose memory included therein is limited in capacity and the like and toa household electrical appliance that does not include even an OS. It isvery difficult for the household electrical appliance and the portabletelephone having a network connecting function but a relatively low dataprocessing capability to implement an advanced protocol as in the caseof the PC to perform a negotiation in communication.

Hence, data appropriate for the capability of the terminal apparatushaving a network connecting function but a relatively low dataprocessing capability cannot be delivered to the terminal apparatus.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been devised to solve problems asdescribed above, and it is an object of the present invention to providea terminal apparatus, a data transmitting apparatus, a data transmittingand receiving system, and a data transmitting and receiving method thatmake it possible to notify the capability of the terminal apparatus anddeliver data appropriate to the capability of the terminal apparatuseven when the terminal apparatus does not have an advanced negotiationfunction.

In order to achieve the above object, according to the presentinvention, there is provided a terminal apparatus connected to a datatransmitting apparatus for transmitting data via a network, the terminalapparatus including: packet transmitting means for transmitting a datarequesting packet requesting transmission of desired data and havinginformation indicating capability of the terminal apparatus attachedthereto to the data transmitting apparatus; data receiving means forreceiving the desired data that is transmitted from the datatransmitting apparatus in response to reception of the data requestingpacket; decoding processing means for decoding the data received by thedata receiving means; and output means for outputting the data decodedby the decoding processing means.

Further, in order to achieve the above object, according to the presentinvention, there is provided a data transmitting apparatus connected toa terminal apparatus via a network, the data transmitting apparatusincluding: packet receiving means for receiving a data requesting packetrequesting transmission of data, the data requesting packet beingtransmitted from the terminal apparatus; detecting means for detectinginformation indicating capability of the terminal apparatus, theinformation being attached to the data requesting packet received by thepacket receiving means; network state information receiving means forreceiving information on a state of the network, the information beingtransmitted from a network monitoring apparatus for monitoring the stateof the network; and data transmitting means for transmitting, via thenetwork, data based on the information indicating the capability of theterminal apparatus detected by the detecting means and the informationon the state of the network received by the network state informationreceiving means.

Further, in order to achieve the above object, according to the presentinvention, there is provided a data transmitting and receiving systemincluding: a terminal apparatus; a data transmitting apparatus; and anetwork monitoring apparatus for monitoring a state of a network, theterminal apparatus, the data transmitting apparatus, and the networkmonitoring apparatus being connected to each other via the network;wherein the terminal apparatus includes: packet transmitting means fortransmitting a data requesting packet requesting transmission of desireddata and having information indicating capability of the terminalapparatus attached thereto to the data transmitting apparatus; datareceiving means for receiving the desired data that is transmitted fromthe data transmitting apparatus in response to reception of the datarequesting packet; decoding processing means for decoding the datareceived by the data receiving means; and output means for outputtingthe data decoded by the decoding processing means; and the datatransmitting apparatus includes: packet receiving means for receivingthe data requesting packet having the information indicating thecapability of the terminal apparatus attached thereto, the datarequesting packet being transmitted from the terminal apparatus;detecting means for detecting the information indicating the capabilityof the terminal apparatus from the data requesting packet received bythe packet receiving means; network state information receiving meansfor receiving information on the state of the network, the informationbeing transmitted from the network monitoring apparatus; and datatransmitting means for transmitting, via the network, data based on theinformation indicating the capability of the terminal apparatus detectedby the detecting means and data of the information on the state of thenetwork received by the network state information receiving means.

Further, in order to achieve the above object, according to the presentinvention, there is provided a data transmitting and receiving method ofa data transmitting and receiving system, the data transmitting andreceiving system including: a terminal apparatus; a data transmittingapparatus; and a network monitoring apparatus for monitoring a state ofa network, the terminal apparatus, the data transmitting apparatus, andthe network monitoring apparatus being connected to each other via thenetwork, the data transmitting and receiving method including the stepsof: the terminal apparatus transmitting a data requesting packetrequesting transmission of desired data and having informationindicating capability of the terminal apparatus attached thereto to thedata transmitting apparatus; the data transmitting apparatus receivingthe data requesting packet transmitted from the terminal apparatus;detecting the information indicating the capability of the terminalapparatus from the data requesting packet received; receivinginformation on the state of the network, the information beingtransmitted from the network monitoring apparatus; and transmitting databased on the detected information indicating the capability of theterminal apparatus and the received information on the state of thenetwork to the terminal apparatus via the network; and the terminalapparatus receiving the desired data transmitted from the datatransmitting apparatus; decoding the received data; and outputting thedecoded data.

As is clear from the above description, the terminal apparatus accordingto the present invention attaches information indicating capability ofthe terminal apparatus to a data requesting packet requestingtransmission of desired data, and then transmits the data requestingpacket to the data transmitting apparatus. Thereby the terminalapparatus can notify the capability of the terminal apparatus. It isthus possible to perform data communication according to the capabilityof the terminal apparatus without a complex protocol or a negotiationstep.

Therefore, even when the terminal apparatus has a minimum capability (aCPU, a memory, and the like), the terminal apparatus with onlytransmitting and receiving means can receive data appropriate for theterminal apparatus from the data transmitting apparatus.

Also, as is clear from the above description, the data transmittingapparatus according to the present invention receives a data requestingpacket transmitted from the terminal apparatus, the data requestingpacket requesting transmission of desired data and having informationindicating capability of the terminal apparatus attached thereto.Thereby the data transmitting apparatus can be informed of thecapability of the terminal apparatus. It is thus possible to performdata communication according to the capability of the terminal apparatuswithout a complex protocol or a negotiation step.

Therefore, the data transmitting apparatus can transmit data appropriatefor the terminal apparatus having a minimum capability (a CPU, a memory,and the like) in addition to the transmitting and receiving means.

Furthermore, the data transmitting apparatus can grasp a state of thenetwork through the network monitoring apparatus. The data transmittingapparatus can therefore transmit the data to the terminal apparatus uponconsideration of a state of congestion of the network and the like.

Further, as is clear from the above description, in the datatransmitting and receiving system according to the present invention,the terminal apparatus attaches information indicating capability of theterminal apparatus to a data requesting packet requesting transmissionof desired data, and then transmits the data requesting packet to thedata transmitting apparatus. Thereby the terminal apparatus can notifythe capability of the terminal apparatus to the data transmittingapparatus. It is thus possible to perform data communication accordingto the capability of the terminal apparatus without a complex protocolor a negotiation step.

Therefore, even when the terminal apparatus has only transmitting andreceiving means and a minimum capability (a CPU, a memory, and thelike), the data transmitting and receiving system according to thepresent invention can transmit data appropriate for the terminalapparatus from the data transmitting apparatus.

Furthermore, the data transmitting apparatus can grasp a state of thenetwork through the network monitoring apparatus. The data transmittingapparatus can therefore transmit the data to the terminal apparatus inconsideration of a state of congestion of the network and the like.

Further, as is clear from the above description, in the datatransmitting and receiving method according to the present invention,the terminal apparatus attaches information indicating capability of theterminal apparatus to a data requesting packet requesting transmissionof desired data, and then transmits the data requesting packet to thedata transmitting apparatus. Thereby the terminal apparatus can notifythe capability of the terminal apparatus to the data deliveringapparatus. It is thus possible to perform data communication accordingto the capability of the terminal apparatus without a complex protocolor a negotiation step.

Therefore, even when the terminal apparatus has only transmitting andreceiving means and a minimum capability (a CPU, a memory, and thelike), the data transmitting and receiving method according to thepresent invention can transmit data appropriate for the terminalapparatus from the data transmitting apparatus.

Furthermore, the data transmitting apparatus can grasp a state of thenetwork through the network monitoring apparatus. The data transmittingapparatus can therefore transmit the data to the terminal apparatus inconsideration of a state of congestion of the network and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects of the invention will be seen by reference tothe description, taken in connection with the accompanying drawing, inwhich:

FIG. 1 is a diagram of assistance in explaining a configuration of adata transmitting and receiving system according to an embodiment of thepresent invention;

FIG. 2 is a diagram of assistance in explaining a profile field fordescribing information indicating capability of a terminal apparatuswhen IPv6 (Internet Protocol version 6) is applied as an IP protocol inthe data transmitting and receiving system;

FIG. 3 is a diagram showing an example of a profile of image datatransmitted to the terminal apparatus in the data transmitting andreceiving system;

FIG. 4 is a diagram showing an example of a profile of image datatransmitted to the terminal apparatus in the data transmitting andreceiving system;

FIG. 5 is a diagram of assistance in explaining a TOS (Type of Service)field for describing information indicating capability of the terminalapparatus when IPv4 (Internet Protocol version 4) is applied as an IPprotocol in the data transmitting and receiving system;

FIG. 6 is a diagram showing a second configuration of the datatransmitting and receiving system;

FIG. 7 is a diagram showing a third configuration of the datatransmitting and receiving system; and

FIG. 8 is a flowchart of assistance in explaining operation of a datatransmitting apparatus in the data transmitting and receiving system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of a terminal apparatus, a data transmittingapparatus, a data transmitting and receiving system, and a datatransmitting and receiving method according to the present inventionwill hereinafter be described in detail with reference to the drawings.

The present invention is applied to a data transmitting and receivingsystem 1 shown in FIG. 1. The data transmitting and receiving system 1has a data transmitting apparatus 10 and a terminal apparatus 20connected to each other via a network.

The network of the data transmitting and receiving system 1 is alsoconnected with a network monitoring apparatus not shown in the figurefor monitoring a state of congestion of the network and the like. Aresult of monitoring by the network monitoring apparatus is transmittedto the data transmitting apparatus 10 via the network regularly or inresponse to a request from the data transmitting apparatus 10.

The data transmitting apparatus 10 is a server apparatus 11 or a videocamera 12, for example, and is an apparatus that has a function ofdistributing data such as contents to the terminal apparatus 20 via thenetwork.

The server apparatus 11 stores a plurality of contents having image datacompression-coded by a predetermined data compression method fortransmission to the terminal apparatus 20, and is able to transmit thecontents stored therein in response to a request from the terminalapparatus 20.

The video camera 12 takes a picture of a subject and generates imagedata by compression coding by a predetermined data compression method.The video camera 12 can record the generated image data onto apredetermined recording medium or transmit the image data to theterminal apparatus 20 via the network in real time.

The data transmitting apparatus 10 such as the server apparatus 11, thevideo camera 12 or the like retains or generates image data that iscompression-coded by a data compression method adopting a layered codingmethod.

Examples of the data compression method adopting the layered codingmethod include MPEG2 (Moving Picture Experts Group Phase 2), MPEG4(Moving Picture Experts Group Phase 4), JPEG (Joint Photographic CodingExperts Group) 2000, Motion JPEG2000, and the like.

The layered coding method is generally a compression coding method thatgenerates, as one coded data file, a base layer, or coded data that canbe decoded by even a low-speed and low-capability terminal apparatus 20to restore an appropriate image, and an enhancement layer, or coded dataadded to the coded data of the base layer so that a high-speed andhigh-capability terminal apparatus 20 can restore an image of highresolution.

MPEG is a moving picture compression method using DCT (Discrete CosineTransform). MPEG2 provides spatial scalability, SNR (Signal to NoiseRatio) scalability, and temporal scalability as parameters allowinglayering. With each of the parameters, the base layer and theenhancement layer are defined.

Spatial scalability is a function assumed to be applied to connectionbetween video standards with different spatial resolutions (numbers ofpixels), for example HDTV (High Definition TeleVision) and SDTV(Standard Definition TeleVision).

With SNR scalability, there are a base layer where DCT coefficientsquantized roughly using a relatively large quantization scale factor arecoded, and an enhancement layer where differential DCT coefficientsobtained by finely quantizing differences between the roughly quantizedDCT coefficients and real DCT coefficients using a relatively smallquantization scale factor are coded. With SNR scalability, two pieces ofimage data having different image qualities can be readily encoded anddecoded.

With temporal scalability, when image data having different frame ratesis mixed, an image having a low frame rate is coded in a base layer, anda frame of image data having a high frame rate, which frame cannot berepresented at the low frame rate, is coded in an enhancement layer.

MPEG4 is a moving picture compression standard intended for coding at avery low bit rate of a few ten kbps (bits per second). Since MPEG4provides higher resistance to errors and can deal with a lowercommunication speed than MPEG2, MPEG4 is a standard that can deal withradio communication of portable terminal apparatus and the like.

Further, since the compression coding method of MPEG4 allows coding on aper-object basis, scalability can be provided for each object. Inaddition, spatial scalability and temporal scalability can be providedfor each object.

Further, MPEG4 is expected to incorporate a Fine Granularity (smallstep) Scalability technique into the standard. This technique enablesimage data from a low bit rate to a high bit rate to be distributedscalably.

JPEG2000 employs an image compression method using wavelettransformation, and provides a plurality of pieces of hierarchical imagedata of different resolutions, such as low resolution, standardresolution, and high resolution, by dividing the image data intofrequency components and performing encoding.

With Motion JPEG2000, it is possible to handle moving images anddistribute data scalably by packetizing into a layered structure.

The data transmitting apparatus 10 receives a data requesting packetrequesting transmission of image data which packet is transmitted fromthe terminal apparatus 20, and then detects information indicatingcapability of the terminal apparatus which information is attached to apredetermined part of the received data requesting packet.

The data transmitting apparatus 10 also receives a result of monitoringof the network transmitted from the network monitoring apparatus notshown in the figure connected to the network. The network monitoringapparatus detects a state of congestion of the network and the like. Thenetwork monitoring apparatus notifies the data transmitting apparatus 10of the state of congestion of the network and the like regularly or inresponse to a request from the data transmitting apparatus 10.

The data transmitting apparatus 10 determines a hierarchical level, abit rate, a frame rate, resolution, a coding/decoding method, colordepth (number of bits) and the like of the image data to be transmittedto the terminal apparatus 20 on the basis of the information indicatingthe capability of the terminal apparatus 20 which information is sentfrom the terminal apparatus 20 and the result of monitoring of thenetwork transmitted from the network monitoring apparatus not shown inthe figure.

Thus, the data transmitting apparatus 10 transmits the determined imagedata to the terminal apparatus 20 via the network. The data transmittingapparatus 10 transmits the image data determined in consideration of thecapability of the terminal apparatus 20 and the state of the network tothe terminal apparatus 20 via the network.

The terminal apparatus 20 is a PC (Personal Computer) or a portabletelephone, for example. The terminal apparatus 20 transmits a datarequesting packet requesting delivery of desired data to the datadelivering apparatus 10 such as the server apparatus 11, the videocamera 12, or the like as mentioned above via the network, and receivesthe image data transmitted in response to the data requesting packet viathe network.

A terminal apparatus 20 a and a terminal apparatus 20 b, for example,are different in capabilities such as image display capability of thedisplay, data processing capability of the CPU, and the like.

The data requesting packet is an IP (Internet Protocol) packet. Theinformation indicating the capabilities of the terminal apparatus 20itself can be attached to a header portion of the IP packet.

The capabilities of the terminal apparatus 20 are for example a bit rateand a frame rate at which the terminal apparatus 20 can performprocessing, resolution of the display of the terminal apparatus 20, adata coding/decoding method that can be carried out, processingcapability of the CPU of the terminal apparatus 20, color depth (numberof bits) that can be represented, and the like.

The terminal apparatus 20 attaches the information indicating thecapabilities of the terminal apparatus 20 to the header portion of theIP packet as follows.

In a case where an IP address of the IP packet is an IPv6 (InternetProtocol version 6) address, for example, the information indicating thecapability of the terminal apparatus 20 is described in an EUI (ExtendedUnique Identification)-64 field as shown in FIG. 2. EUI-64 is a standarddefined by the IEEE (the Institute of Electrical and ElectronicsEngineers inc.). Information in this EUI-64 format is used in 64lower-order bits of a 128-bit IP address of IPv6, the 64 lower-orderbits being assigned as an interface ID.

EUI-64 includes a field of 24 bits describing a company ID and a fieldof 40 bits describing an apparatus ID. First eight bits of the apparatusID of 40 bits is used as a field where data for describing theinformation indicating the capability of the terminal apparatus 20 iswritten.

In the description below, the field describing the informationindicating the capability of the terminal apparatus 20 is referred to asa profile field, and the information indicating the capability of theterminal apparatus 20 is also referred to as a profile.

For example, the information indicating the capability of the terminalapparatus 20 may be described directly in the profile field, or when thedata transmitting apparatus 10 retains a table that relates theinformation indicating the capability of the terminal apparatus 20 to anidentifier for identifying the capability, the identifier may bedescribed in the profile field.

Suppose for example that as in the latter case, the data transmittingapparatus 10 has a table for determining spatial resolution as shown inFIG. 3 as the table that relates the information indicating thecapability of the terminal apparatus 20 to an identifier for identifyingthe capability.

In this case, when the terminal apparatus 20 describes an identifier“2,” for example, in the profile field of a data requesting packet, thedata transmitting apparatus 10 determines that the resolution of theterminal apparatus 20 is SD (Standard Definition: 720×576 resolution).

In order to change image quality level at the same spatial resolution,for example SD (720×576 resolution) the profile is classified accordingto the image quality level as shown in FIG. 4, and a desired imagequality level is described in the profile field of the data requestingpacket. Thereby the quality level of an image desired to be transmittedby the data transmitting apparatus 10 can be requested.

In a case where the IP address of a data requesting packet is an IPv4(Internet Protocol version 4) address, the information indicating thecapability of the terminal apparatus 20 is described in a TOS (Type ofService) field of an IPv4 header, as shown in FIG. 5.

The TOS field is provided to indicate a type of traffic (service)requested by an application layer of the OSI (Open SystemInterconnection) reference model, for example traffic allowing asubstantial delay, traffic requiring real-time transmission or the like.

A profile is described in IPv4 using a Precedence field of the TOSfield, for example. With the profiles described with reference to FIG. 3and FIG. 4, an identifier of zero to seven is described in thePrecedence field, whereby the data transmitting apparatus 10 candetermine the profile of the terminal apparatus 20.

By thus using the TOS field of the IPv4 header, the terminal apparatus20 can transmit the profile, or the information indicating thecapability of the terminal apparatus, to the data transmitting apparatus10.

The data transmitting and receiving system 1 shown in FIG. 1 may be forexample a data transmitting and receiving system 100 as shown in FIG. 6,in which the data transmitting apparatus 10 such as the video camera 12or the like and the terminal apparatus 20 are connected in a one-to-onerelation to each other.

Further, as shown in FIG. 7, the data transmitting and receiving system1 may be configured as a data transmitting and receiving system 200having a repeater 30 on a network.

The repeater 30 is a router or a multicast server, for example. Therepeater 30 receives a data requesting packet transmitted from aterminal apparatus 20 in which packet the profile of the terminalapparatus is described, and thus reads the profile of each terminalapparatus 20. The repeater 30 transmits the read profile to a datatransmitting apparatus 10 via a network. The data transmitting apparatus10 determines data to be transmitted on the basis of the profile, andthen transmits the data to the repeater 30.

The repeater 30 receives the data transmitted from the data transmittingapparatus 10, and then multicasts the received data to the terminalapparatus 20 via the network.

Incidentally, when the terminal apparatus 20 is present on the networkand the repeater 30 receives many profiles, data of all layers may betransmitted to the repeater 30.

Operation of the data transmitting apparatus 10 such as the serverapparatus 11, the video camera 12, or the like will next be describedwith reference to a flowchart of FIG. 8.

At a step S1, the data transmitting apparatus 10 is in a standby statefor a data requesting packet transmitted from the terminal apparatus 20,in which packet a profile, or information indicating capability of theterminal apparatus 20 is described.

When the data transmitting apparatus 10 receives a data requestingpacket transmitted from the terminal apparatus 20, the data transmittingapparatus 10 advances the process to a step S2. When the datatransmitting apparatus 10 does not receive any data requesting packet,the data transmitting apparatus 10 continues to be in the standby state.

At a step S2, the data transmitting apparatus 10 reads the profile ofthe terminal apparatus 20 described in a predetermined part of the datarequesting packet transmitted from the terminal apparatus 20. When thedata transmitting apparatus 10 has read the profile, the datatransmitting apparatus 10 advances the process to a step S4. When thedata transmitting apparatus 10 cannot read the profile, the datatransmitting apparatus 10 advances the process to a step S3.

At the step S3, in response to the fact that the data transmittingapparatus 10 cannot read the profile described in the data requestingpacket, the data transmitting apparatus 10 transmits an error messagenotifying the fact via the network to the terminal apparatus 20 is thesource of a transmission of the data requesting packet. After thetransmission of the error message, the process returns to the step S1.

At the step S4, the data transmitting apparatus 10 receives anotification of a state of congestion of the network and the like fromthe network monitoring apparatus, which is not shown in the figure,connected to the network.

At a step S5, the data transmitting apparatus 10 determines on the basisof the profile read from the data requesting packet at the step S2whether a bandwidth of the network sufficient to transmit image datacorresponding to the capability of the terminal apparatus 20 can beused. When the bandwidth cannot be used, the data transmitting apparatus10 advances the process to a step S6. When the bandwidth can be used,the data transmitting apparatus 10 advances the process to a step S7.

At the step S6, in response to the fact that the bandwidth of thenetwork required to transmit the desired image data is not available,the data transmitting apparatus 10 transmits a message notifying thefact to the terminal apparatus 20 via the network.

At the step S7, the data transmitting apparatus 10 determines forexample a hierarchy, resolution, image quality, frame rate and the likeof the image data to be transmitted, on the basis of the profile readfrom the data requesting packet at the step S2 and the state ofcongestion of the network and the like received at the step S4.

At a step S8, the data transmitting apparatus 10 transmits the imagedata of the characteristics determined at the step S7 via the network tothe terminal apparatus 20 that transmitted the data requesting packet.

At a step S9, the data transmitting apparatus 10 determines whether thetransmission of the image data is completed. When the transmission ofthe image data is completed, the process is ended.

When a request to end the data transmission is transmitted from theterminal apparatus 20 via the network at a step S10, the datatransmitting apparatus 10 immediately ends the transmission of the imagedata.

Thus, the data transmitting apparatus 10 determines the characteristicsof the image data to be transmitted, on the basis of the profiledescribed in the data requesting packet transmitted from the terminalapparatus 20 via the network, which profile is the informationindicating the capability of the terminal apparatus 20, and a result ofmonitoring of the network and the like by the network monitoringapparatus. The data transmitting apparatus 10 then transmits the imagedata to the terminal apparatus 20.

While a preferred embodiment of the invention has been described usingspecific terms, such description is for illustrative purposes only, andit is to be understood that changes and variations may be made withoutdeparting from the spirit or scope of the following claims.

1. A terminal apparatus connected to a data transmitting apparatus fortransmitting data via a network, the terminal apparatus comprising:packet transmitting means for transmitting a data requesting packetrequesting transmission of desired data and including informationindicating a capability of the terminal apparatus; data receiving meansfor receiving the desired data that is transmitted from the datatransmitting apparatus in response to reception of the data requestingpacket; decoding processing means for decoding the data received by thedata receiving means; and output means for outputting the data decodedby the decoding processing means, wherein: the information indicatingthe capability of the terminal apparatus includes layered information, abit rate, a frame rate, a coding/decoding method, processing capabilityinformation, color depth information, and a type of allowed traffic forthe desired data, the type of allowed traffic indicating an amount ofacceptable delay in receiving the data, and the data is received in aformat that is determined based on the capability information and acongestion of the network, wherein when the network congestion exceedsan amount that allows transmission of data according to the capabilityinformation, the format of the data is changed to allow the transmissionof the data according to the network congestion.
 2. A terminal apparatusas claimed in claim 1, wherein the data transmitted from the datatransmitting apparatus is hierarchically coded.
 3. A terminal apparatusas claimed in claim 1, wherein the data requesting packet is an IP(Internet Protocol) packet.
 4. A terminal apparatus as claimed in claim3, wherein the information indicating the capability of the terminalapparatus is described in header information of the IP packet.
 5. Aterminal apparatus as claimed in claim 3, wherein the IP packet is apacket defined by IPv4 (Internet Protocol version 4).
 6. A terminalapparatus as claimed in claim 3, wherein the IP packet is packet definedby IPv6 (Internet Protocol version 6).
 7. A terminal apparatus asclaimed in claim 1, wherein the data received by the data receivingmeans is image data.
 8. A data transmitting apparatus connected to aterminal apparatus via a network, the data transmitting apparatuscomprising: packet receiving means for receiving a data requestingpacket requesting transmission of data, the data requesting packet beingtransmitted from the terminal apparatus; detecting means for detectinginformation indicating a capability of the terminal apparatus, theinformation being included in the data requesting packet received by thepacket receiving means; network state information receiving means forreceiving information on a state of network congestion, the informationbeing transmitted from a network monitoring apparatus for monitoring thestate of network congestion; and data transmitting means fortransmitting, via the network, data based on the information indicatingthe capability of the terminal apparatus detected by the detecting meansand the information on the state of network congestion received by thenetwork state information receiving means, wherein: the informationindicating the capability of the terminal apparatus includes layeredinformation, a bit rate, a frame rate, a coding/decoding method,processing capability information, color depth information, and a typeof allowed traffic for the data, the type of allowed traffic indicatingan amount of acceptable delay in receiving the data, and when the stateof network congestion exceeds an amount that allows transmission of dataaccording to the capability information, the format of the data ischanged to allow the transmission of the data according to the networkcongestion.
 9. A data transmitting apparatus as claimed in claim 8,wherein the data transmitted to the terminal apparatus is hierarchicallycoded.
 10. A data transmitting apparatus as claimed in claim 8, whereinthe data requesting packet is an IP (Internet Protocol) packet.
 11. Adata transmitting apparatus as claimed in claim 10, wherein theinformation indicating the capability of the terminal apparatus isdescribed in header information of the IP packet.
 12. A datatransmitting apparatus as claimed in claim 10, wherein the IP packet isa packet defined by IPv4 (Internet Protocol version 4).
 13. A datatransmitting apparatus as claimed in claim 10, wherein the IP packet isa packet defined by IPv6 (Internet Protocol version 6).
 14. A datatransmitting apparatus as claimed in claim 8, wherein the datatransmitted to the terminal apparatus is image data.
 15. A datatransmitting and receiving system comprising: a terminal apparatus; adata transmitting apparatus; and a network monitoring apparatus formonitoring a state of network congestion, the terminal apparatus, thedata transmitting apparatus, and the network monitoring apparatus beingconnected to each other via the network; wherein the terminal apparatusincludes: packet transmitting means for transmitting a data requestingpacket requesting transmission of desired data and including informationindicating a capability of the terminal apparatus; data receiving meansfor receiving the desired data that is transmitted from the datatransmitting apparatus in response to reception of the data requestingpacket; decoding processing means for decoding the data received by thedata receiving means; and output means for outputting the data decodedby the decoding processing means; and wherein the data transmittingapparatus includes: packet receiving means for receiving the datarequesting packet having the information indicating the capability ofthe terminal apparatus, the data requesting packet being transmittedfrom the terminal apparatus; detecting means for detecting theinformation indicating the capability of the terminal apparatus from thedata requesting packet received by the packet receiving means; networkstate information receiving means for receiving information on the stateof network congestion, the information being transmitted from thenetwork monitoring apparatus; and data transmitting means fortransmitting, via the network, data based on the information indicatingthe capability of the terminal apparatus detected by the detecting meansand the information on the state of network congestion, wherein: theinformation indicating the capability of the terminal apparatus includeslayered information, a bit rate, a frame rate, a coding/decoding method,processing capability information, color depth information, and a typeof allowed traffic for the data, the type of allowed traffic indicatingan amount of acceptable delay in receiving the data, and when the stateof network congestion exceeds an amount that allows transmission of thedata according to the capability information, the format of the data ischanged to allow the transmission of the data according to the networkcongestion.
 16. A data transmitting and receiving system as claimed inclaim 15, wherein the data transmitted from the data transmittingapparatus to the terminal apparatus is hierarchically coded.
 17. A datatransmitting and receiving system as claimed in claim 15, wherein thedata requesting packet is an IP (Internet Protocol) packet.
 18. A datatransmitting and receiving system as claimed in claim 17, wherein theinformation indicating the capability of the terminal apparatus isdescribed in header information of the IP packet.
 19. A datatransmitting and receiving system as claimed in claim 17, wherein the IPpacket is a packet defined by IPv4 (Internet Protocol version 4).
 20. Adata transmitting and receiving system as claimed in claim 17, whereinthe IP packet is a packet defined by IPv6 (Internet Protocol version 6).21. A data transmitting and receiving system as claimed in claim 15,wherein the data transmitted from the data transmitting means of thedata transmitting apparatus and received by the data receiving means ofthe terminal apparatus is image data.
 22. A data transmitting andreceiving method of a data transmitting and receiving system, the datatransmitting and receiving system including: a terminal apparatus; adata transmitting apparatus; and a network monitoring apparatus formonitoring a state of network congestion, the terminal apparatus, thedata transmitting apparatus, and the network monitoring apparatus beingconnected to each other via the network, the data transmitting andreceiving method comprising: the terminal apparatus transmitting a datarequesting packet requesting transmission of desired data and includinginformation indicating a capability of the terminal apparatus; the datatransmitting apparatus receiving the data requesting packet transmittedfrom the terminal apparatus; detecting the information indicating thecapability of the terminal apparatus from the data requesting packetreceived; receiving information on the state of network congestion, theinformation being transmitted from the network monitoring apparatus; andtransmitting data based on the detected information indicating thecapability of the terminal apparatus and the received information on thestate of network congestion to the terminal apparatus via the network;and the terminal apparatus receiving the desired data transmitted fromthe data transmitting apparatus; decoding the received data; andoutputting the decoded data, wherein: the information indicating thecapability of the terminal apparatus includes layered information, a bitrate, a frame rate, a coding/decoding method, processing capabilityinformation, color depth information, and a type of allowed traffic forthe data, the type of allowed traffic indicating an amount of acceptabledelay in receiving the data, and when the state of network congestionexceeds an amount that allows transmission of data according to thecapability information, the format of the data is chanced to allow thetransmission of the data according to the network congestion.